1. Field of the Invention
The present general inventive concept relates to a read device, an image forming apparatus having the same, and a method of controlling the image forming apparatus, which are capable of preventing deterioration of quality of a read image in a process of transferring a document and reading an image of the document.
2. Description of the Related Art
Generally, an image forming apparatus such as a copier, a printer or a facsimile machine includes a reading function to read data recorded on a document.
A method of reading both sides of a document includes a method of reading an image on one side of a document and reading an image on the other side of the document using a single image sensor while changing a transfer direction of the document and a method of reading images on front and back sides of a document transferred along a document transfer path using a plurality of image sensors which are provided on the document transfer path so as to face each other.
Generally, a first transfer roller and a second transfer roller are mounted on a document transfer path. A document is transferred by driving the first and second transfer rollers and information recorded on the transferred document is read by an image sensor. While the document is read, the first and second transfer rollers are driven at the same speed and a read speed of the image sensor is set according to the speed of the transfer rollers. The document is transferred along the transfer path at a transfer speed determined by the first and second transfer rollers.
Due to mechanical tolerance in a process of assembling components of the apparatus, a transfer speed of a document varies and thus the quality of an image read by a fixed image sensor deteriorates. That is, if the transfer speed of the document passing through the image sensor is excessively low, a phenomenon that the length of the read image is increased occurs and, if the transfer speed of the document is excessively high, a phenomenon that the length of the read image is decreased occurs. Thus, the quality of the read image deteriorates.
Accordingly, in order to obtain a high-quality read image, the deterioration of quality of the read image should be corrected.